1. Field
The following description relates to a transmission/reception technology for a continuous phase modulation scheme that is unaffected by nonlinear channel distortion of a terminal amplifier (solid state power amplifier (SSPA)) in a satellite communication system.
2. Description of the Related Art
Satellite communication system is generally defined as a power limited system. Due to a long propagation distance between the ground and a satellite transponder, satellite communication system experiences severe attenuation of signal power, and particularly, even worse signal attenuation by heavy rain since the system uses high frequency band like (Ku/Ka band). Thus, in amplifying a signal, it may preferable to operate an amplifier at a maximum efficiency point, but in practice the amplifier is operated through several back-off attempts at the 1-dB compression point of nonlinear region in order to avoid nonlinear distortion. This causes a problem of reduction in power efficiency. Meanwhile, a continuous phase modulation scheme is not affected by nonlinear distortion, and thus is widely used by the satellite communication system.
However, the continuous phase modulation scheme requires the design of a complicated receiver, and the performance is largely influenced by a channel code to be combined. Therefore, there is a need for a communication apparatus having a design that is not affected by a channel code and being capable of operating under severe channel attenuation conditions.